The present invention is directed to thin biaxially-oriented polyester films having excellent handling performance during film slitting and winding with reduced film roll buckling defects and improved dielectric strength. Films of the present invention provide utility in thermal transfer media, digital stencils, and especially in capacitor applications.
Japanese unexamined patent application 6-34947 published Dec. 20, 1994, by Toray Industries discloses polyester compositions containing cubic calcium carbonate particles to obtain films with excellent sliding properties and wear resistance for magnetic tape applications.
Japanese unexamined patent 5117443 published May 14, 1993, by Maruo Calcium K. K. discloses the use of synthetic cubic calcium carbonate particles as antiblocking agents in synthetic resins including polyester films for magnetic tape applications.
Japanese unexamined patent 5339394 published Dec. 21, 1993, by Nittetsu Kogyo discloses the use of porous synthetic calcium carbonate particles having a calcite crystal structure with diameter from 0.1 to 2.0 microns and a specific surface area of 20 to 300 m.sup.2 /g by BET as an additive for polyester films.